'bahay' originates from 'Proto-Malayo-Polynesian', specifically the word 'balay', where 'balay' meant 'house'.

'bahay' changed from the Austronesian form 'balay' (used in various Philippine and Malayic languages) and eventually became the modern Tagalog word 'bahay' through regular phonological developments in Philippine languages.

Initially, it meant 'house' (or 'dwelling place'), and over time it has retained that core meaning while also extending to mean 'household' or 'home' in some contexts.